In vacuum furnace technology, it is well understood that after a workpiece has been heated to a prescribed temperature and held thereat for a predetermined period, the desired microstructure for the workpiece is very often dependent on a quick quench. Quick quenches are accomplished in a number of different ways. At least one popular way includes providing a heat exchanger which accepts quenches gas from the hot zone. The heat exchanger removes heat from the quench gas, which has passed over the workpiece, before such gas is returned to the hot zone to remove more heat from the workpiece.
In the prior art such heat exchangers have been and are located at the end of the hot zone. In the event such a heat exchanger was, or is, in need of maintenance, the hot zone has been, or is, removed. In the course of removing a hot zone, generally, a good deal of damage is done because there are many parts of a hot zone which become brittle with use. Such parts easily break in response to being moved, or in response to unscrewing the many sections that are secured to the furnace chamber. Other parts (i.e. other than the heat exchanger) of the internal system require maintenance, such as the bearings of the fan motor which drives the fan that removes the quench gas from the hot zone. In the prior art if a motor bearing required lubrication, sections of the furnace had to be removed if they were in alignment with the fan motor, i.e. located between the motor and the door of the furnace.
The present configuration is the first arrangement, known to the inventors, wherein the heat exchanger itself and its accessibility makes the maintenance easily accomplished. The formation of the heat exchanger per se and its proximity to a removable, sealable port cover does not require the user to remove the hot zone. In addition the present arrangement is the first arrangement, known to the present applicants, which permits the user to readily lubricate the bearings of a fan motor.